A blockchain distributed database is used by the drones to verify delivery information and the identity of fellow drones.

The patent calls for a system allowing a drone to exchange authentication signals with another using “blockchain keys”. If the first recognises its “co-worker,” it passes the package on for the second to deliver.

The keys for recognition would come in the form of a wifi signal, QR code or visual characteristics of the drones, the patent said. The subsequent interactions would take place using delivery information stored on a blockchain database.

By cutting out the need for a “trusted third party,” it says, it would speed up authentication and make online deliveries faster.

With the patent technology, “a first mobile autonomous electronic device wirelessly communicates with a second mobile autonomous electronic device and receives a set of identification information associated with the second mobile autonomous electronic device,” the document said.

John Frazer, chief commercial officer of blockchain company DAV, said it was “encouraging” to see Walmart moving into drone delivery alongside Amazon, which has tested the technology for several years.

By integrating blockchain, Walmart’s application had the potential to “improve drone utilisation and revenue generation,” he said, but transactions needed to be “near real-time, automated and completely binding to ensure efficiencies are achieved”.

“In order for this technology to succeed in real world scenarios, both regulations and infrastructure need to rapidly improve,” he said.

“Having many companies each utilising their own facilities, technology and modus operandi is excellent for creating competition, but ultimately inefficient for the industry to maintain and expensive for consumers. What is needed is a more integrated network to accelerate the implementation of drone deliveries to the same level as traditional parcel logistics.”

Walmart’s application had the potential to “improve drone utilisation and revenue generation,” he said, but the transaction needed to be “near-real-time, automated and completely binding to ensure efficiencies are achieved”.